Battery pack for cordless device

ABSTRACT

A battery pack 13 (FIG. 2) comprises an elongated cylindrical, metal casing 35, a plurality of cells 41, 43 in casing 35 and three coaxial pack terminals 46, 54, 61. For enhanced convenience, pack terminals 46, 54, 61 are electrically connectable in a cordless device 11 regardless of the angular orientation of the pack 13 about casing axis 33. To reduce cost and increase durability, pack 13 has no welded connections and will permit high current discharge rates. Cells 41, 43 are electrically connected but are mechanically disconnected. A spring 73 engages cell 41 and biases cells 41, 43 tightly together in compression to form good, low resistance electrical contact between cells 41, 43, casing base cap 45 and top 53. To provide a pack with two output voltages, the third pack terminal 61 has a polarity (relative to first pack terminal 46) the same as second pack terminal 54 and is electrically connected to the cell can terminal 43b of forward cell 43, thereby electrically by-passing cell 43.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 08/239,437,filed May 6, 1994, now U.S. Pat. No. 5,489,454; which is a continuationof Ser. No. 08/065,736, filed May 21, 1993, and now abandoned; which isa continuation-in-part of Ser. No. 08/042,937, filed Apr. 5, 1993, andnow abandoned.

FIELD OF THE INVENTION

The invention relates to a cordless (i.e, battery-operated) device suchas a power tool or kitchen appliance. More particularly, the presentinvention relates to a battery pack and receptacle for mounting the packin the device.

BACKGROUND OF THE INVENTION

For the consumer market, most cordless devices have a battery pack madeintegrally in the device housing because of reduced cost, increased enduser convenience and sturdiness. However, because of the desire toprovide consumer devices with detachable packs simplifying the recyclingof the packs and the desire to provide a family of cordless devicesusing an interchangeable pack and a single charger, there is strongcommercial interest in developing a sturdy, convenient, low cost,compact and easily automated battery pack. Of course, these design goalsare not unique to consumer devices but also are equally desirable forprofessional cordless devices in which detachable packs have been thestandard for many years.

SUMMARY OF THE INVENTION

Accordingly, a primary object of the present invention is to provide animproved battery pack and receptacle for mounting the pack in a cordlessdevice embodying the foregoing design objectives.

In accordance with one aspect of the invention, a battery pack comprisesan elongated cylindrical casing with a longitudinal axis of symmetry, aplurality of cells in the casing and first and second pack terminalshaving opposite polarities, coaxial with the casing axis and locatedadjacent to the casing forward end. The pack terminals are electricallyconnectable in a cordless device regardless of the angular orientationof the pack about the casing axis. Such a pack provides greater end userconvenience.

Preferably the casing is metal, is electrically connected to a firstcell terminal of a rear cell in the pack and constitutes the first packterminal. The second pack terminal is preferably a top disposed acrossthe casing forward end. To provide shielding for the pack terminals, thetop preferably defines a cavity in the casing forward end and has aforwardly projecting nipple fully recessed within the casing cavity.

Alternatively, the second pack terminal may be formed by a buttonterminal of a forward cell exposed at the casing forward end.

Alternatively, the second pack terminal may be formed by a shieldedfemale barrel-shaped terminal fully recessed within the casing cavity.

To provide a pack with multiple output voltages, a third pack terminalmay be located in the casing cavity coaxially of the casing axis, have apolarity the same as the second pack terminal and be electricallyconnected to a first cell terminal of a forward cell in the pack therebyelectrically by passing the forward cell.

In accordance with a second aspect of the invention, a battery packcomprises a tubular metal casing, a metal base cap closing the rear end,and a fixed abutment formed in and closing the casing forward end. Aplurality of electrically connected, mechanically disconnected cells aredisposed end to end in the casing. The metal base cap is electricallyconnected to and mechanically disconnected from an adjacent rear celland forms with the casing a first pack terminal. A second pack terminalis located at the casing forward and is electrically connected to anadjacent forward cell. A spring engages one of the cells and biases thecells tightly together in compression to form good electrical contactbetween adjacent cells and pack terminals to permit high currentdischarge rates. Such a pack has no welded connections and is,therefore, more reliable and lower in cost.

The abutment preferably is a lip formed at the forward end of the casingto terminate the casing and retain the cells and pack terminals incompression. To provide a pack with multiple output voltages, a thirdpack terminal is preferably compressed between the casing lip and aforward cell. The third terminal may be formed as a sleeve having (a)axial fingers engaging the forward cell can and (b) transverse fingersoverlapping and helping to secure the top.

Alternatively, the abutment may be formed by an annular bead formed inthe casing slightly forwardly of the forward cell.

The second pack terminal is preferably a metal top closing the casingforward end electrically connected to and mechanically disconnected froma button terminal of the forward cell. Alternatively, the second packterminal may be constituted by the button terminal of the forward cellexposed at the casing forward end. Alternatively, the second packterminal may be formed by a shielded female barrel-shaped terminal fullyrecessed within the casing cavity.

The spring is preferably formed integrally in the base cap but may alsobe a separate component.

In accordance with a third aspect of the invention, battery packs inaccordance with either the first or the second aspect of the inventiondescribed above may include an integral plastic plug containing thesecond and third pack terminals separated by an insulating wall. Thesecond terminal is preferably a tubular nipple filled with plastic andfurther preferably covered by a plastic projection extending forwardlyfrom the forward end of the nipple.

In accordance with a fourth aspect of the invention, a cordless devicecomprises a cavity, a receptacle in the cavity and a battery pack inaccordance with either the first, second or third aspect of theinvention described above. The pack is electrically connectable in thereceptacle regardless of the angular orientation of the pack about thecasing axis.

The receptacle preferably comprises a housing defining a cavity having alongitudinal axis coaxial to the casing axis when the pack is mounted inthe receptacle. The receptacle further includes an appropriate number ofreceptacle terminals for mating with a pack having either two or threepack terminals.

The receptacle terminals are preferably coaxially located about thereceptacle cavity axis.

Additional objects and advantages of the invention will be apparent fromthe detailed description of the preferred embodiment, the appendedclaims and the accompanying drawings or may be learned by practice ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings which are incorporated in and constitute apart of, this specification illustrates eight embodiments to the presentinvention and together with the description serve to explain theprinciples of the invention. In the drawings, the same referencenumerals indicate the same parts.

FIG. 1 is a top plan view of a cordless device in accordance with thepresent invention.

FIG. 1A is an enlarged view of a portion 1A of FIG. 1.

FIG. 2 is an axial cross-sectional view of the battery pack in thecordless device in FIG. 1.

FIG. 2A is a perspective view of a third terminal for the battery packin FIG. 2.

FIG. 3 is an rear elevational view taken along line 3--3 of FIG. 2.

FIG. 4 is a front elevational view taken along line 4--4 of FIG. 2.

FIG. 5 is a fragmentary axial cross-sectional view of an secondembodiment of a battery-pack in accordance with the present invention.An alternative base cap connection for the pack in FIG. 2 is shown.

FIG. 6 is a fragmentary axial cross-sectional view of a third embodimentof a battery pack in accordance with the present invention. Anotheralternative base cap connection for the pack of FIG. 2 is shown.

FIG. 7 is a top plan view of a receptacle for the cordless device ofFIG. 1 in accordance with the present invention.

FIG. 8 is a cross-sectional view of the receptacle taken along line 8--8of FIG. 7.

FIG. 9 is a cross-sectional view of the receptacle taken along line 9--9of FIG. 7.

FIG. 10 is a top plan view of a fourth embodiment of a battery pack inaccordance with the present invention.

FIG. 11 is a cross-sectional view of the pack taken along line 11--11 ofFIG. 10.

FIG. 12 is a fragmentary cross-sectional view showing a fifth embodimentof a battery pack and one terminal of a compatible receptacle inaccordance with the present invention.

FIG. 13 is a fragmentary cross-sectional view of a sixth embodiment of abattery pack and one terminal of a compatible receptacle in accordancewith the present invention.

FIG. 14 is a fragmentary cross-sectional view showing a seventhembodiment of a battery pack in accordance with the present invention.

FIG. 15 is a top plan view of an eighth embodiment of a battery pack inaccordance with the present invention.

FIG. 16 is a fragmentary cross-sectional view of the pack taken alongline 16--16 of FIG. 15.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of the present invention is a cordless (i.e.,battery operated) device such as a kitchen appliance or a power tool.One example of such a device is a cordless screwdriver 11 as shown inFIG. 1. The preferred embodiment, more particularly, is an improvedbattery pack 28 (FIGS. 15, 16) and an improved receptacle 15 (FIGS. 7-9)for electrically connecting battery pack 28 in device 11. Sevennonpreferred embodiments of battery packs 13, 17, 19, 21, 22, 24, 26 inaccordance with the present invention, are shown in FIGS. 2-6 and 10-14.

As shown in FIGS. 1-4, in accordance with the present invention,cordless device 11, here exemplified as an inline screwdriver, comprisesa housing 23 for receiving battery pack 13, a motor (not shown), anoutput spindle 25, a gear train (not shown) intermediate the motor andspindle 25, and a receptacle 15 for electrically connecting pack 13 tothe motor through a motor control circuit (not shown) including on/offand speed control switch 27. Housing 23 further includes, a generallycylindrical cavity 29 in a handle portion 31 of housing 23 for receivingpack 13 and receptacle 15. According to one aspect of the presentinvention, the battery pack 13 is removably located in cavity 29 and iselectrically connectable to receptacle 15 regardless of the angularorientation of pack 13 about a longitudinal axis of symmetry 33 of pack13. (This aspect of the invention is sometimes referred to hereinafteras the "universal angular orientation feature"). Pack 13 is thus easierto use and may be easily loaded in device 11 under adverse conditionssuch as in dim light or in cramped quarters.

Pack 13 comprises an elongated cylindrical tubular metal casing 35having opposed rear and forward ends 37, 39. A plurality of electricallyconnected, mechanically disconnected cells 41, 43 are disposed end toend in casing 35. For simplicity, pack 13 is illustrated in FIG. 2 withtwo cells 41, 43. However, the present invention is equally applicableto packs including two or more cells. Each cell, 41, 43 has a cell can41a, 43a for forming a first cell terminal and a button terminal 41b,43b closing one end of the cell and forming a second cell terminal. Asis conventional, the first or cell can terminal 41a, 43a is negative andthe second or button terminal 41b, 43b is positive. Cells 41, 43 arepreferably nickel-cadmium cells which are preferred for high dischargerate applications (5 to 30 amps) such as power tools and certain kitchenappliances. However, the present invention is also equally applicable toother rechargeable and primary cell couples such as nickel metal hydrideor primary alkaline cells.

A metal base cap 45 (FIGS. 2, 3) closes casing rear end 37 and iselectrically connected to and mechanically disconnected from the rearcell 41 adjacent casing rear end 37 and forms one pack terminal 46. Theconnection between base cap 45 and casing 35 may be made in a number ofdifferent ways. A one way serrated snap fit connection 49 depicted inFIG. 2 is preferred. Alternative connections are, for example, a onepiece connection 47 depicted in FIG. 5 and a removably threadedconnection 51 depicted in FIG. 6. Connection 49 permits cells 41, 43 tobe loaded through casing rear end 37 and thereafter base cap 45 is fixedto casing 35 and is not removable for end user servicing. A one piececonnection 47 (FIG. 5) is used when assembly of the cells through casingforward end 39 is desired. If end user servicing of the pack 13 isdesired, for example, when primary cells are used, removably threadedconnection 51 (FIG. 6) may be used.

Through the connection of metal base cap 45 to metal casing 35, any partof casing 35 may be utilized as the first cell terminal 46. Oneadvantage of the present invention is that casing 35 is coaxial of thepack longitudinal axis 33 and a coaxial portion of casing 35 adjacent tocasing forward end 39 may be utilized as the first pack terminal 46. Inprior art packs, a strap is usually welded between a forwardly locatedterminal and the rearmost cell of the pack. In the present invention,because casing 35 forms pack terminal 46, a welded strap is notrequired.

A metal top 53 closes the casing forward end 39, is electricallyconnected to button terminal 43b and forms a second pack terminal 54.Top 53 is radially symmetrical about casing axis 33 and defines a cavity55 in the casing forward end 39. A forwardly projecting nipple 57 formedon top 53 is fully recessed within casing cavity 55 and terminatesrearwardly of a forward edge 59 of casing 35. Top 53 is electricallyconnected to and mechanically disconnected from forward cell 43 throughengagement with button terminal 43b.

As will be appreciated, first and second pack terminals 46, 54 haveopposite polarities (preferably, negative and positive, respectively),are coaxial with the casing axis 33 and are located adjacent to thecasing forward end 39. And, for those reasons, pack 13 is easilyconnectable in cordless device 11 regardless of the angular orientationof pack 13 about pack axis 33.

In accordance with another feature of the present invention, the first,second and a third coaxial pack terminals 46, 54, 61 (FIG. 2) arecoaxial with the pack longitudinal axis 33 and are located adjacent tocasing forward end 39. The first pack terminal 46 has a polarityopposite to the polarity of the second and third pack terminals 54, 61.The output voltage between the first and second pack terminals 46, 54 isgreater than the output voltage between the first and third packterminals 46, 61. In the present embodiment, the first pack terminal 46is electrically connected to the first cell terminal 41a of rear cell41. The second pack terminal 54 is electrically connected to the secondterminal 43b of forward cell 43. The third pack terminal 61 iselectrically connected to the first terminal 43a of the forward cell 43and is, in turn, electrically connected to the second terminal 41b ofrear cell 41 thereby electrically by-passing forward cell 43 andproviding an output voltage (relative to the first pack terminal 46)which is less than the output voltage between first and second packterminals 46, 54.

For a two cell pack as depicted in FIG. 2, the first pack terminal 46 isnegative. The second and third pack terminals 54, 61 are positive andhave respectively relative to first pack terminal 46 an output voltage(for Ni-Cd cells) relative to first pack terminal 46 of 1.2 volts and2.4 volts, respectively. Thus, pack 13 in accordance with the presentinvention is particularly advantageous for use in cordless devices suchas a screwdriver, mixer or drill where multiple power settings aredesirable.

As shown in FIGS. 2, 2a, third pack terminal 61 is preferably formed asa sleeve 65 located in casing cavity 55 coaxially of casing axis 33.Sleeve 65 has axial fingers 67 in engagement with the forward cell can43a and transverse fingers 71 overlapping and helping to secure the top53. An insulator 72 insulates top 53 from transverse fingers 71. (FIG.2A shows a rear perspective view of sleeve 65.)

In accordance with another aspect of the present invention, cells 41,43, metal base cap 45 constituting the first pack terminal 46 and metaltop 53 constituting the second pack terminal 54 are electricallyconnected but mechanically disconnected. Good electrical contact betweenadjacent cells 41, 43 and terminals 46, 54 for low resistance, highcurrent discharge rates is achieved through a spring 73 engaging one ofthe cells 41 and biasing the cells 41, 43 tightly together incompression in metal casing 35.

A fixed abutment 75 is formed in casing forward end 39, extends inwardlyof the periphery of forward cell 43 and retains cells 41, 43 incompression in casing 35.

For the present invention, a high discharge rate is defined as betweenabout 5 to 30 amps. A low resistance is defined as less than onemilliohm. To achieve a suitable low resistance of less than onemilliohm, a force of at least 10 to 15 pounds is required to beestablished by spring 73.

As embodied herein, fixed abutment 75 is constituted by a lip 75 formedat the forward end 43 of casing 35. Third pack terminal 61 is compressedbetween casing lip 75 and forward cell 43 to provide good electricalcontact to one terminal of forward cell 43. Thus, pack 13 has no weldedconnections and, therefore, has a lower cost compared to other batterypacks particularly suited for high discharge rate applications.

Spring 73 is preferably integrally formed in base cap 45 and has aplurality of transverse arms 74 engaging rear cell can 41a.Alternatively, as shown in FIGS. 5, 6, the spring may be formed as anindependent component such as coil spring 76 compressed between base cap43 and rear cell 41.

To electrically insulate each cell 41, 43 from casing 35, each cell 41,43 is enclosed within an electrically insulating sleeve 77, 79. Becausecell 41 is at the same potential as casing 13, insulating sleeve 77serves only to provide a uniform outer cell diameter for mechanicallylocating cells 41, 43 in casing 13. Alternatively, as shown in FIG. 6,insulating sleeves 77, 79 may be replaced by a layer of electricalinsulation 81 laminated to an inner wall 83 of casing 13. Layer 81 maybe applied to casing wall 83 through a conventional coating process. Ifit is desired to recharge pack 13 with a temperature cutoff chargetermination circuit, the material for electrically insulating sleeves77, 79 is chosen to have a high thermal conductivity. By using thermallyconductive sleeves in combination with metal casing 35, pack 13 hasenhanced thermal conductivity. And during charging, the temperature ofpack 13 can be more accurately measured by a thermally responsive devicein the charge termination circuit.

As shown in FIGS. 7-9, receptacle 15 electrically connects packs 13 indevice 11 regardless of the angular orientation of pack 13 about packaxis 33. Receptacle 15 has a housing 85 defining a cavity 87 having alongitudinal axis 89 coaxial to pack axis 33 when the casing forward end39 is mounted in cavity 87. Receptacle 15 further includes a firstu-shaped receptacle terminal 91 adjacent housing 85 for resilientlyclamping first pack terminal 46, a second u-shaped receptacle terminal93 adjacent to the receptacle cavity axis 89 for mating with second packterminal 54 and a third u-shaped receptacle terminal 95 intermediate thefirst and second receptacle terminals 91, 93 for resiliently engagingthird pack terminal 61. Each receptacle terminals 91, 93, 95 extendsoutwardly from cavity 87 and is radially symmetrical about axis 89. Thefirst receptacle terminal 91 has a central opening 97 which surrounds ahousing post 99. Third receptacle terminal 95 has a central opening 101which surrounds post 99. An insulating washer 103 surrounds post 99 andelectrically insulates first and third terminals 91, 95. A cup-shapedinsulator 105 is supported on the top of post 99 and supports secondreceptacle terminal 93 at the bottom and electrically insulates secondand third receptacle terminals 93, 95. An axially extending rivet 107integrally connects first, second and third receptacle terminals 91, 93,95 and insulators 103, 105.

To electrically connect first, second and third receptacle terminals 91,93, 95 in a motor control circuit (not shown) of device 11, eachterminal 91, 93, 95 has respectively an integrally formed blade 111,113, 115 extending through an end wall 109 of housing 85.

FIGS. 10 and 11 show a nonpreferred fourth embodiment of a battery pack21 having first and second pack terminals 123, 125 which are coaxialwith a longitudinal pack axis 127, are located adjacent to a casingforward end 129 and are electrically connectable to a receptacle (notshown) regardless of the angular orientation of pack 21 about casingaxis 127. Pack 121 does not share with pack 13 two of the other primaryfeatures achievable in pack 13, the preferred embodiment, namely, anonwelded construction and multiple output voltages.

Pack 21 comprises an elongated cylindrical casing 131 havinglongitudinal axis of symmetry 127 and having opposed rear and forwardends 133, 129. In this embodiment, casing 131 is preferably constructedof plastic molded in a clam shell configuration with a parting line (notshown) lying in an axially extending plane. A plurality of cells 135,137 are mounted in casing 131. Cells 135, 137 are preferably identicalto cells 41, 43. The first pack terminal 123 is formed as a sleeve 139located in a casing cavity 141. A first or positive cell terminal 143 iselectrically connected to pack terminal 123 through a metal strap 145spot welded to cell terminal 143 at one end and to pack terminal 123 atthe other. Strap 145 lies in an axially extending channel 146 in casing131. Channel 146 opens externally of casing 131 and electricallyinsulates strap from cells 135, 137.

Pack terminal 125 is preferably formed as a narrow tubular pin 147 spotwelded to the second or negative can terminal 149 of cell 137. Acylindrical wall 151 is located between terminals 123, 125 and reducesthe likelihood of shorting terminals 123, 125. Furthermore, wall 151 maybe used to actuate a shutter or shield for preventing inadvertentcontact with the terminals of a battery charger for pack 121.

Pack 21 may be used with a receptacle similar to that shown in FIGS. 7-9except that receptacle terminal 91 would be omitted as pack 21 has onlytwo coaxial terminals 123, 125 rather than three.

FIG. 12 shows a nonpreferred fifth embodiment of a battery pack 22 inaccordance with the present invention. Pack 22 has first, second andthird pack terminals 155, 157, 159 which are coaxial with a longitudinalpack axis 161 and are electrically connectable to a receptacle (notshown) regardless of the angular orientation of pack 22 about pack axis161. Pack 22 is identical to pack 13 except for the construction ofsecond and third pack terminals 157, 159 and thus shares with pack 13three of the primary features achievable in pack 13, the preferredembodiment, namely, universal angular orientation, a nonweldedconstruction and multiple output voltages.

The second pack terminal 157 is constituted by a button terminal 163 ofa forward cell 165 adjacent casing forward end 167.

The third pack terminal 159 is electrically connected to first or canterminal 169 of the forward cell 165 and is, in turn, electricallyconnected to a second button terminal of a rear cell (not shown) therebyelectrically bypassing forward cell 165 and providing an output voltage(relative to the first pack terminal 155) which is less than the outputvoltage between first and second pack terminals 155, 157.

Third pack terminal 159 is preferably formed as a sleeve located in acasing cavity 171 and is compressed between casing lip 173 and forwardcell 165 to provide good electrical contact to first can terminal 169 offorward cell 165.

Pack 22 may be used with a receptacle (not shown) identical to thatshown in FIGS. 7-9 except that second receptacle terminal 93 would bereplaced by a coil spring terminal 175 (shown in FIG. 12). Spring 175 isanchored in the receptacle. And thus, FIG. 12 illustrates only themanner for making electrical contact to second pack terminal 157 whenpack 22 is inserted in a cordless device. An advantage provided by pack22 compared to pack 13 is that pack 22 utilizes button terminal 63 asthe second pack terminal rather than a separate top 53 for the secondpack terminal 54 in pack 13 (FIG. 2). And thus, pack 22 requires fewerparts and assembly steps.

FIG. 13 shows a nonpreferred sixth embodiment of a battery pack 24according to the present invention. Pack 24 has first and second packterminals 179, 181 which are coaxial with a longitudinal axis 183, arelocated adjacent to a casing forward end 185 and are electricallyconnectable to a receptacle (not shown) regardless of the angularorientation of pack 24 about pack axis 183. Pack 24 is identical to pack13 except for the construction of second pack terminal 181 and theomission of a third pack terminal for providing a second output voltage.Thus, pack 24 shares with pack 13 two of the primary features achievablein pack 13, the preferred embodiment, namely, a nonwelded constructionand a universal angular orientation.

Second pack terminal 181 is constructed identically to second packterminal 157 of pack 22 (FIG. 12) and is constituted by a buttonterminal 187 of forward cell 189.

By omission of a third pack terminal in pack 24, the cells 189 arebiased tightly together in compression in metal casing 191 between abase cap (not shown) and an annular bead 193. Bead 193 is formed incasing 191 slightly forwardly of forward cell 189, extends radiallyinwardly of the periphery of cell 189 and serves as a fixed abutment forretaining the cells in compression.

Pack 24 may be used with a receptacle similar to that shown in FIGS. 7-9except that (a) second receptacle terminal 93 would be replaced by acoil spring terminal 195 identical to coil spring terminal 175 providedfor pack 22 and (b) third receptacle terminal 95 would be omittedbecause of the omission of the third pack terminal in pack 24.

FIG. 14 shows a nonpreferred seventh embodiment of a battery pack 26 inaccordance with the present invention. Pack 26 has first, second andthird pack terminals 195, 197, 199 which are coaxial with a longitudinalpack axis 201 and are electrically connectable to a receptacle (notshown) regardless of the angular orientation of pack 26 about pack axis201. Pack 26 is identical to pack 13 except for the construction ofsecond pack terminal 199 and insulator 203 and the addition ofsupplemental insulator 204. And thus, pack 26 shares with pack 13 threeof the primary features achievable in pack 13, the preferred embodiment,namely, universal angular orientation, a nonwelded construction andmultiple output voltages.

The second pack terminal 197 is constituted by a female, open ended,barrel-shaped, axially slotted terminal 197 that is press fitted on abutton terminal 205 of a forward cell 207 adjacent casing forward end209. To provide increased resistance to inadvertent short circuitingbetween second pack terminal 197 and either third pack terminal 199 orfirst pack terminal 195, insulator 203 (which electrically insulates thesecond and third pack terminals 197, 199) completely surrounds an outerwall 211 and a forward edge 213 of barrel terminal 197. Also, insulator204 surrounds the inner edge of casing forward end 209 to enchance theshielding between pack terminals 195, 199.

Pack 26 may be used with a receptacle (not shown) identical to thatshown in FIGS. 7-9 except that second receptacle terminal 93 (FIG. 8)would be replaced by a pair of closely spaced, cantilevered springfingers (not shown) which extend generally parallel to receptacle axis89 and are bowed convexly outwardly relative to axis 89. When pack 26 isplugged into the receptacle (not shown), the fingers would resilientlyengage an inner wall 215 of barrel terminal 197. Alternatively,receptacle terminal 93 may be replaced by a pin (not shown) extendingcoaxially of axis 89.

FIGS. 15 and 16 show a preferred eighth embodiment of a battery pack 28in accordance with the present invention. Pack 28 has first, second andthird pack terminals 219, 221, 223 which are coaxial with a longitudinalpack axis 225 and are electrically connectable to a receptacle (notshown) regardless of the angular orientation of pack 28 about pack axis225. Pack 28 is identical to pack 13 (FIG. 2) except for theconstruction of second pack terminal 221 and a plug 227 for integrallyjoining second terminal 221 and third terminal 223 (identical to thirdterminal 61 of pack 13) and incorporating an electrically insulatingwall 229. And thus, pack 28 shares with pack 13 three of the primaryfeatures achievable in pack 13, the preferred embodiment, namely,universal angular orientation, a nonwelded construction and multipleoutput voltages.

The second pack terminal 221 is constituted by a metal top 231terminating in a forwardly projecting, open ended, tubular nipple 233.Top 231 is press fitted on a button terminal 235 of a forward cell 237adjacent casing forward end 239. To provide increased resistance toinadvertent short circuiting between second pack terminal 221 and eitherthird pack terminal 223 or first pack terminal 219, annular insulatingwall 229 surrounds nipple 233 and separates third terminal sleeve 223and nipple 233. The top 231, sleeve 223 and insulating wall 229 areintegrally molded to form plug 227 in accordance with conventionalplastic injection insert molding techniques. Plug 227 is compressedbetween the casing abutment 241 at the forward end of plug 227 andbutton terminal 231 and cell can 243 of forward cell 237 at the rear endof plug 227.

To further enhance the resistance to short circuiting, nipple 233 isfilled with plastic and has a plastic projection 245 that extendsforwardly from and covers the top of nipple 233.

Pack 28 may be used with a receptacle (not shown) substantiallyidentical to that shown in FIGS. 7-9 except that cup-shaped insulator105 must be eliminated or reconfigured to permit insulating wall 229 ofpack 28 to be received within receptacle cavity 87.

In accordance with the present invention, the disclosed pack terminalsand receptacle terminals and their variants suitable for providing theuniversal angular orientation of the pack and receptacle may be definedas terminal means for electrically connecting the pack and receptacletogether regardless of the angular orientation, relative to thereceptacle, of the pack about the casing axis. It will be recognizedthat there are a number of suitable variants. For example, to accomplishthe universal angular orientation, preferably, (a) the pack terminalsare coaxial about the pack axis, (b) the receptacle terminals arecoaxial about the receptacle axis and (c) when the pack is inserted inthe receptacle, the pack axis and receptacle axis are coaxial. However,only one of the sets of terminals (the pack terminals constituting oneset and the receptacle terminals constituting the second set) must becoaxial. For example, each receptacle terminal may be constituted by aflat blade positioned to be resiliently engageable with a mating packterminal of a coaxial set of pack terminals. Thus, in this example, thepack terminals are coaxial about a longitudinal pack axis and thereceptacle terminals are not coaxial about a longitudinal receptacleaxis. Furthermore, continuous annular members are used to form thecoaxial pack terminals in packs 13, 21, 22, 24, 26, 28 and discontinuousannular members are used to form the receptacle terminals.Alternatively, discontinuous annular members may be used to form thepack terminals and continuous annular members may be used to form thereceptacle terminals. In accordance with the present invention, all ofthese terminal configurations are included in the definition of theterminal means.

As will be appreciated by those skilled in the art, a number ofadvantages flow from the present invention. Namely, packs 13, 21, 22,24, 26, 28 have two or more coaxial terminals permitting the packs to beconnected in a cordless device regardless of the angular orientation ofthe pack about its axis. As a result, packs 13, 21, 22, 24, 26, 28 areeasier to use particularly under adverse conditions for loading the packin a cordless device or charger. Additionally, because packs 13, 21, 22,24, 26, 28 have no preferred angular orientation, the packs areparticularly suited for complete enclosure within a cordless device.This is particularly desirable, for example, in certain householdappliances where the requirement of an exposed battery pack limitsindustrial design freedom.

Secondly, packs 13, 22, 24, 26, 28 provide a lower cost, more reliablebattery pack particularly suited for high discharge rate applicationsthrough the elimination of the welded connections between adjacent cellsand pack terminals. In prior art packs, welded connections are a commonsource of pack failure. Packs 13, 22, 24, 26, 28 also potentially have alower cost than prior art packs because the enclosure of the cellswithin a metal casing which is sealed by a rolled over lip 75 or bead193 permits the manufacturing process to be easily varied to accommodatepacks having different lengths based on the number of cells in the pack.

Finally, the three coaxial pack terminals 46, 54, 61; 155, 157, 159permit the selective and easy connection of different numbers of cellsin the motor control circuit of a cordless device. Thus, packs 13, 22are particularly suited for applications requiring multiple powersettings. Other advantages will be apparent to those skilled in the art.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the cordless device andbattery pack of the present invention without departing from the scopeor spirit of the invention. Thus, it is intended that the presentinvention cover these modifications and variations provided they comewithin scope of the appended claims and their equivalents.

We claim:
 1. A battery pack comprising:a casing having a longitudinalaxis and having opposed rear and forward ends; a plurality of cells inthe casing, each cell having first and second cell terminals; and firstand second pack terminals having opposite polarities, coaxial with thecasing axis, located adjacent to the casing forward end and electricallyconnectable in a cordless device regardless of the angular orientationof the pack about the casing axis.
 2. The pack recited in claim 1,wherein, the forward end of said casing is open and a cavity is definedwithin the casing at the open forward end, and said second pack terminalis disposed within the cavity and terminates rearwardly of said openforward end.
 3. The pack recited in claim 1, said casing beingcylindrical, each said first cell terminal comprising a cell can andeach said second terminal comprising a cell button, wherein, the buttonterminal of the forwardmost cell is exposed at the casing forward endand constitutes the second pack terminal.
 4. The pack recited in claim3, wherein, the forward end of said casing is open and a cavity isdefined within the casing at the open forward end, and said buttonterminal of the forwardmost cell terminates rearwardly of said openforward end of said casing within the cavity.
 5. The pack recited inclaim 1, said pack further comprising an electrically conducting strapwelded at one end to the first pack terminal and at the other end to thefirst cell terminal of a rearwardmost cell.
 6. The pack recited in claim1 further comprising a third pack terminal.
 7. The pack recited in claim1, said casing being cylindrical, said first and second pack terminalsdisposed symmetrically about said longitudinal axis.
 8. A cordlessdevice comprising:a cavity; a receptacle in the cavity; a battery packremovably located in the cavity and comprising a casing and a pluralityof cells in the casing, said casing having a longitudinal axis andhaving opposed rear and forward ends, each cell having first and secondcell terminals; and terminal means for electrically connecting the packand receptacle together regardless of the angular orientation, relativeto the receptacle, of the pack about the casing axis.
 9. The devicerecited in claim 8, said casing being cylindrical and said terminalmeans including first and second pack terminals disposed coaxially aboutthe casing axis.
 10. The device recited in claim 9, said terminal meansincluding a third pack terminal disposed coaxiaily about the casingaxis.
 11. The device recited in claim 9, wherein, said receptacle has ahousing defining a receptacle cavity having a longitudinal axis coaxialto the casing axis and receiving the casing forward end; andthe terminalmeans comprises further comprising first and second receptacle terminalscoaxial to the receptacle axis and mating respectively with the firstand second pack terminals.
 12. A cordless device comprising:a cavity; areceptacle disposed in the cavity, said receptacle having a housingdefining a receptacle cavity, the receptacle cavity having alongitudinal axis; a first receptacle terminal disposed within thereceptacle cavity; a second receptacle terminal disposed within thereceptacle cavity; and a battery pack removably located in the cavity,said battery pack including an elongated cylindrical casing having alongitudinal axis of symmetry coaxial to the longitudinal axis of thereceptacle cavity and opposed rear and forward ends, a plurality ofcells disposed in the casing, and first and second pack terminals, eachsaid cell having first and second cell terminals; wherein, said firstreceptacle terminal mates with the first pack terminal and said secondreceptacle terminal mates with the second pack terminal, the packterminals are coaxial with the casing axis, and the pack terminals arelocated adjacent to the casing forward end and are electricallyconnectable to the receptacle terminals regardless of the angularorientation of the battery pack about the casing axis.
 13. The devicerecited in claim 9, said terminal means including a third pack terminaldisposed coaxiaily about the casing axis.
 14. A cordless devicecomprising:a longitudinally extending cavity; a receptacle disposed inthe cavity, said receptacle having a housing defining a receptaclecavity, the receptacle cavity having a longitudinal axis; a firstreceptacle terminal disposed within the receptacle cavity; a secondreceptacle terminal disposed within the receptacle cavity; wherein, abattery pack having front and rear ends and first and second packterminals disposed adjacent the front end is slidably locatable in thereceptacle cavity with the longitudinal axis of the battery pack coaxialto the longitudinal axis of the receptacle cavity and with the firstreceptacle terminal matable with the first pack terminal and the secondreceptacle terminal matable with the second pack terminal in any angularorientation of the pack about the coaxial longitudinal axes.
 15. Thedevice recited in claim 14, wherein, said first receptacle terminal isspaced at a first radial distance from the longitudinal axis of thereceptacle cavity, the second receptacle terminal is space at a secondradial distance from the longitudinal axis of the receptacle cavity withthe second radial distance being greater than the first radial distance,the battery pack has a casing having an overall radius which issubstantially the same as the second radial distance, and the batterypack is locatable in the receptacle cavity with second receptacleterminal disposed in contact with an exterior surface of the casing.